Recurrent and second primary squamous cell carcinoma of the head and neck: When and how to reirradiate

Background. Local and/or regional recurrence and metachronous primary tumor arising in a previously irradiated area are rather frequent events in patients with head and neck squamous cell carcinoma (HNSCC). Re-treatment is associated with an increased risk of serious toxicity and impaired quality of life (QOL) with an uncertain survival advantage. Methods. We analyzed the literature on the efficacy and toxicity of photon/electron-based external beam reirradiation for previously irradiated patients with HNSCC of non-nasopharyngeal origin. Studies were grouped according to the radiotherapy technique used for reirradiation. Patient selection criteria, target volume identification method, tumor dose, fractionation schedule, systemic therapy administration, and toxicities were reviewed. Results. In addition to disease-related factors, current comorbidities and preexisting organ dysfunction must be considered when selecting patients for reirradiation. As morbidity from re-treatment may be considerable and differ depending on which mode of re-treatment is used, it is important to give patients information on potential morbidity outcomes so that an informed choice can be made within a shared decisionmaking context. With improved dose distribution and adequate imaging support, including positron emission tomography-CT, modern radiotherapy techniques may improve local control and reduce toxicity of reirradiation. A reirradiation dose of 60 Gy and a volume encompassing the gross tumor with up to a 5-mm margin are recommended. Concomitant administration of systemic therapeutics and reirradiation is likely to be of similar benefit as observed in large randomized studies of upfront therapy. Conclusion. Reirradiation, administered either with or without concurrent systemic therapy, is feasible and tolerable in properly selected patients with recurrent or a new primary tumor in a previously irradiated area of the head and neck, offering a meaningful survival (in the range of 10% to 30% at 2 years). Whenever feasible, salvage surgery is the method of choice for curative intent; patients at high-risk for local recurrence should be advised that postoperative reirradiation is expected to increase locoregional control at the expense of higher toxicity and without survival advantage compared to salvage surgery without reirradiation.